The Collaborative International Dictionary of English v.0.48:

Uninterested \Un*in"ter*est*ed\, a.
   1. Not interested; not having any interest or property in;
      having nothing at stake; as, to be uninterested in any
      business.
      [1913 Webster]

   2. Not having the mind or the passions engaged; as,
      uninterested in a discourse or narration.
      [1913 Webster]

WordNet (r) 3.0 (2006):

uninterested
    adj 1: not having or showing interest; "an uninterested
           spectator" [ant: interested]
    2: having no care or interest in knowing; "she appeared totally
       uninterested"

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "uninterested":
   Laodicean, Olympian, aloof, apathetic, ataractic, benumbed, blah,
   blase, bored, bored stiff, bored to death, bored to tears,
   careless, casual, comatose, desensitized, detached, devil-may-care,
   disinterested, dispassionate, disregardful, distant, dull,
   easygoing, heartless, hebetudinous, heedless, hopeless, impassive,
   in a stupor, inattentive, incurious, indifferent, inexcitable,
   insouciant, lackadaisical, languid, lethargic, listless, mindless,
   negligent, nonchalant, numb, numbed, passive, perfunctory,
   phlegmatic, pluckless, pococurante, reckless, regardless, remote,
   resigned, slack, sluggish, soporific, spiritless, spunkless, stoic,
   stolid, stupefied, stuporous with boredom, supine, torpid,
   turned-off, unanxious, uncaring, unconcerned, undiscriminating,
   uninquiring, uninvolved, unmindful, unsolicitous, withdrawn